Modeling Neurological Disease with Human iPS Cell-Derived Neurons Containing a KCNT1 Mutation

Abstract

The sodium-activated potassium channel Slack, encoded by the gene KCNT1, is expressed in neurons throughout many brain regions, including the frontal cortex, and mediates a sodium-sensitive potassium current (IKNa). This outward current regulates neuronal excitability and determines how neurons respond to repeated high frequency stimulations, both of which are aspects of memory and learning. Not surprisingly, mutations in KCNT1 and alterations to the IKNa current have patho-physiological consequences. Recent studies have described the emerging role of Slack channels in cognitive deficits, and several reports have found KCNT1 mutations in patients with severe early onset “childhood” epilepsies.The development of better therapies for neurological disorders has been hindered by limited access to clinically-meaningful cell models for research and drug development. The advent of induced pluripotent stem (iPS) cell technology provides a platform to facilitate increased understanding of disease mechanisms in a physiologically-relevant environment. We have leveraged this technology to generate human neurons that express the KCNT1 P924L mutation in the Slack channel. To introduce this alteration, we genetically engineered a “control” iPS cell line from an apparently healthy donor with no family history of neurological disorders and generated highly purified (>95% TUJ1-positive), terminally differentiated cortical neurons from the two separate but isogenic iPS cell lines.Here, we present data on the characterization of these human neurons, including expression of a standard set of neuronal markers at both the genetic and protein level. We also highlight functional testing of the cells, with a specific focus on electrophysiological readouts such as multi-electrode array (MEA) analysis. The ability to model neurological disorders through editing the genome of an iPS cell and subsequently produce previously inaccessible human neurons has revolutionized the way we approach studying and treating diseases of the central nervous system.